The rims look like they use schrader vavles and that is a tip off to probably low end and 27" wheels. If everything on it is wore out it matters little what it is. I have bought near mint bikes from thrift stores and garage sales that needed nothing but tires and tubes for less than $50. A junker for $75 is no deal.
I was lucky to get $50 for a mid 80's Fuji similar to that one and on mine everything worked! Thrift stores, yard sales or classified ads are the best route for that price point. There's nothing on that bike really worth chunking any cash into. Even then you'd have to really scrounge for the low-end out of date parts.